An X-ray computed tomography apparatus is preferably designed to minimize the vibration of the gantry which is generated when the gantry rotates, in order to improve image quality. To scan a moving organ such as the heart of a human body with good image quality, it is necessary to rotate the gantry at high speed. However, as the rotational speed of the gantry increases, the vibration of the gantry increases.
As measures to reduce vibration accompanying the rotation of the gantry, there are known a method of adjusting the rotation/forward-backward balance of the gantry rotating unit by using an adjustment weight, a method of increasing the rigidity of the frame of each gantry portion, and the like.
The market needs concerning recent X-ray computed tomography apparatuses are to reduce the outer shape sizes and weights of X-ray computed tomography apparatuses which can rotate at high speed. That is, there are no market needs to simply increase the sizes and weights of the frames of the respective gantry portions to increase the rigidity of the frames.